The present invention relates generally to apparatus and methods for cooking foods, particularly with respect to means and techniques to avoid burning or overcooking of sensitive portions of foods. In its preferred embodiments, the present invention relates more specifically to apparatus and methods for cooking foods on an automated basis, such as in a fast food restaurant, utilizing a conveyor for transporting foods through a heated cooking area.
As the pace of modern society has quickened over recent years, consumer demand has resulted in a proliferation of restaurants of the type and style specializing in rapid preparation and service of limited and typically specialized food menus without the usual restaurant amenities of waiters or waitresses and like services, now commonly referred to as fast-food restaurants. In such restaurant establishments, the speed and rate of food preparation is of the essence. A variety of techniques are employed among various fast-food restaurants to meet this goal. Among others, it is not uncommon for restaurants, particularly in baking or broiling foods, to increase cooking temperature in order to achieve a corresponding decrease in required cooking time. This technique, however, is effective to only a relatively limited extent because the risk of burning or overcooking sensitive portions of food items also increases considerably as the cooking temperature is increased. Thus, the range of food items which fast-food restaurants can effectively prepare and serve has been somewhat limited. For example, pizzas typically require a preparation and cooking time which can typically range from ten to twenty minutes, even more, depending upon the number and type of pizza toppings, the type of pizza crust used, and the cooking temperature. Experience has shown that attempts to increase cooking temperature to achieve a decrease in cooking time commonly result in overcooking and often burning of the exposed outer pizza crust which is not covered with any topping. Accordingly, restaurants specializing in pizzas have been limited in their ability to compete directly with other more traditional fast food establishments.
Over recent years, consumers have also become increasingly concerned with fat and cholesterol content of many common and popular foods, particularly meats. As a result, the rate of consumption of leaner types of meats, particularly chicken and other poultry, has been progressively increasing. At the same time, the methods by which meat and other foods are prepared is now viewed as being of equal importance, oil-based frying of foods being disfavored because it substantially increases the fat content of prepared foods while broiling of foods has become increasingly popular since this preparation method involves no addition of fat to the food.
Disadvantageously, however, the increased popularity of broiling as a food preparation method poses several problems for restaurant owners and others involved in commercial and large-scale preparation of foods. One of the most common commercial food broiling systems utilizes a grill suspended over a heat-generating source, typically a gas-fueled burner. During the cooking of virtually any meat on such a broiling apparatus, fat rendered from the meat falls onto the burner producing a considerable amount of smoke, fire and fumes, all of which must be exhausted from the cooking area. In order to do so in many restaurants and other large-scale food preparation operations, it is necessary to maintain high rates of air exhaust from the cooking area, generally through an exhaust flue and filtering arrangement. While a sufficiently high rate of air exhaust is sufficient in most cases to maintain the cooking and serving areas of restaurants and like establishments substantially free of smoke and fumes, the operators of such establishments incur substantially increased equipment and operational expenses for both the exhaust system and for air conditioning and heating the establishment. Further, various Federal, State and/or local laws and regulations prohibit the direct release of the exhausted effluent of the cooking process into the ambient atmosphere. Accordingly, an air filtering arrangement of a capacity suitable to handle air at the prevailing rate of exhaust must be utilized, additionally increasing the cost of operation. Finally, broiling apparatus of this basic type generally require an operator with a reasonably high level of skill and experience to attend the meat being cooked on the apparatus to insure sufficient cooking without overcooking and burning of the meat.
Various types of automated cooking apparatus have been proposed wherein meat is transported by a continuous conveyor system between vertically-oriented opposed facing burners or other cooking elements to reduce the generation of smoke and fumes while at the same time automating the cooking process. Representative examples of such apparatus are disclosed in U.S. Pat. Nos. 2,718,188 to Read et al; 3,646,879 to Palmason et al; 4,366,182 to Kohler et al; and 4,753,216 to Nolte. Of these apparatus, only the Kohler et al patent contemplates use of such an apparatus for cooking whole chickens or other relatively large irregularly-shaped meat items, the apparatus of the other patents being particularly designed and intended for broiling steaks, chops, hamburgers and the like.
One of the most important criteria for the commercial acceptability of any such apparatus is that the meat item must be uniformly cooked over its entire mass. Since many common meat items are typically of a non-uniform thickness and have a non-uniform distribution of fat (with the possible exception of hamburger patties), this criteria is difficult to reliably achieve on a repeatable regular basis in a commercial setting utilizing an apparatus of the type of the above-identified patents wherein substantially the same amount of cooking heat energy is applied by the opposed burners to all exposed surfaces of the meat item without regard to any inherent irregularities in shape, thickness and fat content of the meat.
This problem would be particularly acute in the broiling of whole chickens as contemplated in the Kohler patent due to the irregular shape of chickens and the irregular distribution of fat, which is concentrated under the skin of the chicken in the region of the thighs and back. In this respect, conventional grill-type broiling apparatus have a notable advantage over conveyorized apparatus of the type of the above-identified patents in that a skilled attendant can regulate the uniformity of cooking of meat items by continuously turning the meat items and changing their position on the grill.